Referring to FIG. 1, a system 100 of the prior art for testing interconnect for stress-migration failure includes a heating chamber 102 with a temperature controller 104. The interconnect structure includes a test line 106 and a feeder line 108. The test line 106 is coupled to the feeder line 108 by a via structure 110 that is part of the dual damascene structure of the test line 106. The temperature controller 104 is used for controlling the temperature within the heating chamber 102, and such a heating chamber is known to one of ordinary skill in the art of integrated circuit fabrication.
When the interconnect structure including the test line 106, the feeder line 108, and the via structure 110 is heated to a range of from about 150° Celsius. to about 350° Celsius. for example, a void 112 forms within the feeder line 108 below the bottom of the via structure 110 from mechanical stress at the interface between the feeder line 108 and the bottom of the via structure 110, as known to one of ordinary skill in the art of integrated circuit fabrication. The test line 106 is coupled to a first test pad 114, and the feeder line 108 is coupled to a second test pad 116. The test line 106, the feeder line 108, the via structure 110, and the first and second test pads 114 and 116 are typically fabricated on a semiconductor wafer that is placed within the heating chamber 102 (and that is not shown in FIG. 1 for clarity of illustration).
Further referring to FIG. 1, a resistance meter 118 is coupled between the first and second test pads 114 and 116 for measuring a resistance across the test line 106, the feeder line 108, and the via structure 110 between the first and second test pads 114 and 116. Such a resistance meter is individually known to one of ordinary skill in the art of electronics. Formation of the void 112 within the feeder line 108 below the bottom of the via structure 110 from stress-migration causes an increase in the resistance measured by the resistance meter 118.
As the interconnect structure having the test line 106, the feeder line 108, and the via structure 110 is heated within the heating chamber 102, a stress-migration life-time is determined when the resistance measured by the resistance meter 118 reaches a threshold resistance level, as known to one of ordinary skill in the art of integrated circuit fabrication. During such stress-migration testing, the interconnect structure having the test line 106, the feeder line 108, and the via structure 110 is continuously heated within the heating chamber 102, and a periodic resistance measurement is made by the resistance meter 118.
In the prior art, no current is continuously conducted through the interconnect structure having the test line 106, the feeder line 108, and the via structure 110 as such an interconnect structure is continuously heated within the heating chamber 102. A relatively small level of current may be conducted through the feeder line 108, the via structure 110, and the test line 106 during the periodic resistance measurements by the resistance meter 118. Such a prior art stress-migration testing system and method may require a burdensome long period of time before the interconnect structure having the test line 106, the feeder line 108, and the via structure 110 exhibits stress-migration failure, such as more than one thousand hours for example.
Nevertheless, during characterization of an integrated circuit fabrication process, the stress-migration life-time of interconnect structures is desired to be determined. Thus, a mechanism is desired for testing for the stress-migration life-time of interconnect structures in less amount of time.